It is frequently desirable to provide an electromechanical interface between an alphanumeric data line, such as from a computer or a word processor, and a general-purpose keyboard device, such as a typewriter or an adding machine. An example of such an arrangement is shown in Stine U.S. Pat. No. 3,029,919, in which an array of solenoids are arranged with their armature axes extending vertically above the keys of the keyboard, one solenoid for each key. The solenoids are individually actuated in response to signals fed to an electrical matrix. An auxiliary keyboard provided above the solenoid array permits manual operation of the underlying keyboard with the interface remaining in place. Such a system is entirely impractical in that the auxiliary keyboard is so high as to render it practically useless to an operator accustomed to a standard keyboard. In addition the very large number of solenoids required makes the system inordinately expensive.